Treatment of calcified ostial disease by rotational atherectomy and adjunctive cutting balloon angioplasty prior to stent implantation

Both heavily calcified and ostial lesions are difficult to deal with by percutaneous transluminal coronary angioplasty (PTCA) alone. Acute results are often sub-optimal, complications are more frequent, and long-term results are disappointing. Optimal stent deployment may not be possible unless satisfactory lesion dilatation is achieved and the lesion made more compliant. The use of rotational atherectomy and cutting balloon angioplasty to a calcified ostial lesion in the left circumflex coronary artery prior to stent implantation is reported.     

Long period of balloon inflation and the implantation of stents potentiate smooth muscle cell death. Possible role of chronic vascular injury in restenosis

BACKGROUND: It has been suggested that the severity of acute vascular injury immediately after percutaneous transluminal coronary angioplasty (PTCA) or stent implantation correlates with the extent of neointimal hyperplasia and restenosis. However, the influence of prolonged or chronic vessel injury on the pathogenesis of restenosis is unclear. METHODS: Rabbit iliac arteries were balloon dilated for a short (1 min) or prolonged (10 min) period of time, or were chronically dilated and received a Palmaz-Schatz stent (balloon inflation for 1 min). All arteries were overexpanded to a balloon:artery ratio of 1.2:1 as determined by angiography. The arteries were removed 30 min and 4 weeks after the angioplasty procedures. The sites of injury were evaluated by gross histology and transmission electron microscopy (TEM). Cell death of medial smooth muscle cells (SMCs) was specified by TEM images 30 min after the procedures. Computer-assisted quantification of the neointimal cross-sectional areas was performed after 4 weeks using a light microscope connected to a digital image analyser. RESULTS: The results show that prolonged balloon dilatation and stent implantation increased necrotic SMC death compared with balloon dilatation for 1 min. After 30 min, increased staining of SMC nuclei, enlarged intercellular spaces and changes in SMC shape in the media indicated cell death induced by prolonged balloon dilatation or chronic stent injury. Stent implantation markedly augmented vessel damage by persistent compression of the media, compared with a balloon dilatation for 1 or 10 min. Both prolonged balloon dilatation and stent implantation increased neointimal hyperplasia at 4 weeks compared with balloon dilatation for 1 min (0.6 3 0.2 and 1.0 3 0.2 mm(2) versus 0.2 3 0.1 mm(2), P < 0.001 versus dilatation for 1 min). CONCLUSION: Prolonged or chronic vascular expansion due to long balloon-inflation periods or the implantation of stents increases medial SMC death, which subsequently stimulates neointimal growth in this restenosis model. Chronic vascular injury may be an important stimulus for restenosis after angioplasty procedures.     

Coronary pressure and FFR predict long-term outcome after PTCA

Although coronary stents have been the most important improvement in percutaneous coronary interventions in the last 10 years, it is well known to interventionalists that many patients after percutaneous transluminal coronary angioplasty (PTCA) have a favourable outcome without stenting. Coronary angiography, however, is not sensitive enough to identify those particular patients and it has been suggested that a combination of angiographic and functional criteria would be more suitable to distinguish patients with a low restenosis chance after plain balloon angioplasty. In the present study, the authors investigated the value of coronary pressure measurement for conditional stenting in 85 patients. It was demonstrated that in patients in whom a high fractional flow reserve (FFR) was present (> 0.90), the incidence of coronary events at two-year follow-up was almost three times lower than in those patients with an FFR below 0.90. Such high FFRs could be obtained in approximately 45% of all patients. In an additional group of patients, it was demonstrated by intravascular ultrasound (IVUS) studies that the mechanism of a high FFR after plain balloon angioplasty is most likely the result of a larger lumen compared with patients with a suboptimal FFR. This means that, in patients in whom both the angiographic and the functional result after PTCA is optimal, a restenosis rate is achieved similar to that achieved by stenting. Obviously, in such patients, additional stenting and a number of problems in the long-term possibly related to stenting can be avoided. Therefore, coronary angiography and coronary pressure measurement have a complementary value in the evaluation of PTCA results and such information can be easily obtained by using a pressure wire instead of a regular guidewire.     

Intravascular brachytherapy to prevent restenosis: dosimetric considerations.

Acute myocardial infarction is often the result of occlusion of one or more coronary arteries. Occlusion and restenosis (re-closing of the vessel) are principal reasons that percutaneous transluminal coronary angioplasty (PTCA) may fail to provide long-term benefit. PTCA has been a popular treatment, which is less invasive than surgeries involving revascularization of the myocardium, promising a better quality of life for patients. Unfortunately, the rate of restenosis after balloon angioplasty is high (approximately 30-50% in the first year after treatment). Recent data suggest that intraluminal irradiation of coronary arteries in conjunction with balloon angioplasty and/or stent implantation reduces the proliferation of smooth muscle cells and neointima formation, thereby inhibiting restenosis. In order to study radiation dosimetry in the patient and for this therapy, dose distributions for electrons and photons, with discrete energies, were simulated for blood vessels of diameter 1.5, 3 and 4.5 mm irradiated with balloon and wire sources. Electron and photon transport was performed in a simple model representing the system used for irradiation using the MCNP 4B code (Monte Carlo N-Particles). Specific calculations for balloon and wire sources were also carried out for a few radionuclides. In this work, strengths and drawbacks conceming the use of each radionuclide simulated, as well as source geometries are discussed. The dosimetry performed in this study will improve understanding of the benefit-to-risk ratio in intracoronary brachytherapy.     

Intravascular-ultrasound-guided percutaneous transluminal coronary angioplasty/provisional stent implantation strategy: impact on long-term clinical follow-up

Two hundred and eighty-four consecutive patients with 438 native coronary artery stenoses were enrolled prospectively in a study of intravascular ultrasound (IVUS)-guided percutaneous transluminal coronary angioplasty (PTCA) with provisional stenting: (1) aggressive lesion-site media-to-media balloon-sizing; (2) IVUS-assessment of residual lumen dimensions to identify optimal PTCA results (minimum lumen area = 65% of the average of the proximal and distal reference lumen areas or = 6.0 mm(2) and no major dissection); and (3) liberal stent crossover. Overall, 206 stenoses in 134 patients (47%) were treated with PTCA alone. Reasons for crossover were flow-limiting or lumen-compromising dissections in 28% of patients and suboptimal IVUS minimum lumen area in 72% of patients. At one year, 8% of stenoses in the PTCA group and 16% in the stent crossover group required revascularization. In approximately half of the patients treated using an IVUS-guided aggressive PTCA strategy, stent implantation could be avoided without sacrificing an increase in acute complications or worse clinical outcome.     

Provisional stenting in small vessels

Based on the currently available data, the strategy of routine stent placement in unselected lesions located in small coronary arteries provides good immediate results but is still associated with a high incidence of in-stent restenosis. Randomized trials comparing elective stenting with balloon angioplasty have not provided the demonstration that routine stenting is the best strategy for percutaneous intervention in coronary arteries with a reference diameter smaller than 2.75-3.0 mm. This paper describes the rationale for provisional stenting in this clinical setting and reviews the role of quantitative coronary angiography, intracoronary ultrasound and intracoronary Doppler measurements in the identification of lesions that would benefit from adjunctive stent placement after balloon angioplasty and in guiding stent implantation.     

Analysis of the transient expansion behavior and design optimization of coronary stents by finite element method

The percutaneous transluminal coronary angioplasty (PTCA) assisted with stenting technique has become a primary therapy to coronary heart disease. In practice, the structure conditions of both ends of stent/balloon system influence a stent's instantaneous expansion behavior. The transitory nonuniform expansion, the so-called dogboning, of stent/balloon system is one of the main reasons to induce the acute vascular injury at the two edges of a stent. This kind of vascular injury has a close relationship with the in-stent restenosis. In the present paper, the finite element method (FEM) was applied to simulate the transient expansion process of stent/balloon system with different stent structure and balloon length under the internal pressure. And two types of stent and six collocations of stent and balloon were modeled. Modeling results showed that the dogboning phenomenon can be eliminated by improving geometry of a stent or/and varying the length of balloon over stent. The above modeled results were further confirmed by following in situ observation.     

Long-term clinical outcome after stent implantation in coronary arteries

The long-term clinical outcome after planned and unplanned stent implantation was assessed in a single-center, observational study in 178 patients who underwent coronary stent implantation between November 1986 and July 1994. Main outcome measures were survival and event-free survival at 5 years (Kaplan-Meier method). Independent predictors for event-free survival were determined by using multivariate logistic regression analysis. Patients underwent planned (group 1, n 3 101) or unplanned (group 2, n 3 77) stent implantation. During the in-hospital period, there were no deaths. The incidence of Q-wave and non-Q-wave acute myocardial infarction (AMI), coronary artery bypass graft (CABG) and repeat percutaneous transluminal coronary angioplasty (PTCA) was 5.0%, 2.0% and 4.0%, respectively, in group 1, versus 32.5%, 23.4% and 10.4%, respectively, in group 2. During the follow-up period (median 4.0 years, range 0.29-9.8 years), the incidence of death, AMI, and repeat revascularization (CABG and PTCA) was 5.9%, 8.9% and 40.6%, respectively, in group 1, versus 1.3%, 5.2% and 36.4%, respectively, in group 2. Survival and event-free survival at 5 years was 73 (7%) and 47 (7%), respectively, for patients who underwent planned stent implantation. It was 98 (0.1%) and 34 (6%), respectively, for patients who underwent unplanned stent implantation. At the end of follow-up, 31.9% of patients had angina pectoris class III or IV (Canadian Cardiovascular Society). The long-term clinical outcome after both planned and unplanned stent implantation was characterized by a high incidence of repeat revascularization. It is conceivable that changes in stent design and implantation techniques, in addition to novel therapeutic approaches addressing neointima formation and progression of atherosclerosis, may improve the long-term clinical outcome.     

Efficiency of endovascular re-interventions for evolving restenosis of different types of stents

The paper compares the results of different treatment options (balloon angioplasty and restenting) for in-stent restenosis in case of evolving restenosis of drug- and nondrug eluting stents. The investigation enrolled 496 coronary heart disease patients with clinical presentation of angina pectoris and/or signs of myocardial ischemia, as well as hemodynamic restenosis of a previously implanted stent. Of them, 216 and 280 patients had restenosis of previously implanted drug- and nondrug-eluting stents, respectively. In the patients with non-drug-eluting stent restenosis, recurrent angina pectoris and the frequency of repeated restenosis were significantly more frequently observed after balloon dilatation than after drug-eluting stent implantation (28.4 and 10.2%; p < 0.05; 19.9 and 8.7%; p < 0.05). In those with drug-eluting stent restenosis, recurrent angina pectoris and the frequency of repeated restenosis did not differ significantly between balloon dilatation of restenosis and implantation of a second drug-eluting stent.     

Initial and long-term results with the CrossFlex stent--data from a national registry

The Cordis CrossFlex trade mark stent is a balloon expandable helical coil made of stainless steel. OBJECTIVE: To assess the short- and long-term safety and efficacy of this stent by conducting a multi-center national registry. METHODS: One hundred and sixteen stents were implanted in 109 patients (mean age 59 3 10 years, 95 males). The lesions were classified as type B2 or C in 56 patients (51%). Successful deployment was achieved in 103 patients (94.5%). Failure was due to damage to the stent (two patients) or inability to reach the lesion (four patients). High-pressure deployment (>14 atm) was used in 68% of cases. RESULTS: Edge dissections occurred in nine patients after high-pressure deployment and necessitated implantation of a second stent. One patient with a large acute myocardial infarction died during hospitalization. Side branch occlusion occurred in five patients (4.6%). Subacute thrombosis occurred in two patients (1.8%) during the first four weeks. During a six-month follow-up period, 18 patients (16.5%) were rehospitalized with recurrent angina. Fifteen patients had coronary angiography and 13 (12.1%) needed additional target lesion revascularization (TLR). Twelve patients required a second PTCA for in-stent restenosis, and one needed a coronary artery bypass graft operation. CONCLUSIONS: The CrossFlex coronary stent can successfully be used in complex coronary lesions, with few short-term complications and a low TLR rate. Operators should be aware of the possibility of edge dissection during high-pressure implantation.     

Comparison of ReoPro((R)) (abciximab) versus intracoronary thrombolysis for early coronary stent thrombosis

AIMS: This study evaluated the treatment of early coronary stent thrombosis with intracoronary urokinase or the platelet glycoprotein IIb/IIIa receptor inhibitor ReoPro (abciximab). METHODS AND RESULTS: Seventy-four patients (126 stents) were treated immediately after identification of early (0-30 days) coronary stent thrombosis. Twenty-nine patients were treated with intracoronary urokinase (UK) (UK alone in 19; UK and additional balloon angioplasty in 10) and another 45 patients were given ReoPro((R)) (abciximab) (0.25 mg/kg as a bolus alone in 26, abciximab with additional balloon angioplasty in 19) within 30 days of stent implantation. TIMI grade 3 flow was obtained in 23 patients (79%) in the UK group and in 38 (84%) in the abciximab group (nonsignificant). Three patients (10%) in the UK group and one (2%) in the abciximab group underwent repeat percutaneous transluminal coronary angioplasty (PTCA) (nonsignificant). Five patients (17%) in the UK group and three (7%) in the abciximab group were referred for urgent coronary artery bypass graft surgery (CABG) because of residual thrombus and refractory ischemia (nonsignificant). Repeat revascularization was necessary in eight patients (28%) in the UK group versus four (9%) in the abciximab group (p < 0.05). Five patients (17%) in the UK group and eight (18%) in the abciximab group developed myocardial infarction (nonsignificant). Five patients (17%) in the UK group (cardiogenic shock (three), cerebral hemorrhage (one) and pneumonia (one)) and three (6.6%) in the abciximab group (cardiogenic shock (two), heart failure (one)) died within 30 days (nonsignificant). Overall, noncardiac complications (bleeding including surgical repair of groin) were observed in 11 patients (38%) in the UK group and three (7%) in the abciximab group (p < 0.001). CONCLUSION: Compared to urokinase, abciximab reduced the need for repeat revascularization procedures and the risk of noncardiac events, including bleeding complications in patients with early coronary stent thrombosis.     

Coronary stent implantation without balloon predilatation: a single-center experience

OBJECTIVE: Assessment of safety and efficacy of coronary stent deployment, without balloon predilatation. BACKGROUND: With newer high-performance balloon-premounted stents it has become more common to attempt coronary stent deployment without balloon pre- or postdilatation. METHODS: During 1998 524 coronary angioplasties were performed in the authors' institute, of which 279 resulted in coronary stenting. Of these 101 (36.2%) were stents without balloon predilatation (SWBP). PTCA was performed according to standard technique using mostly 7 F. guiding catheters, and 'rapid exchange' balloons and pre-mounted stents. RESULTS: Seventy-two patients had acute coronary syndromes (41 acute MI or post-MI angina, 28 unstable angina, 10 rescue PTCA after failed thrombolysis). Mean age was 56.4 3 11.1 years, 84.5% were males. Sixty per cent of the lesions were ACC-AHA type B2 or C. Target arteries were LAD 57.6%, LCX 21.2%, RCA 14.1% and SVG 7.1%. Procedure time was 18.2 3 17.3 minutes. Mean heparin dose was 3850 3 1570 units. Twenty-two patients received abciximab prior to stent deployment. Seven stents were not deployed without previous balloon dilatation and were retrieved safely via the guiding catheters and deployed after balloon dilatation. There was no stent embolization, ectopic suboptimal or partial stent deployment. Immediate angiographic success was obtained in 95 patients (94.1%). Minimal lumin diameter (MLD) increased from 0.27 3 0.15 to 3.23 3 2.1 mm. There were two in-hospital deaths (1.9%) due to cardiogenic shock. An intra-aortic balloon pump was required in eight patients. Two patients (1.9%) experienced subacute stent thrombosis. CONCLUSION: SWBP in selective groups of patients and lesions is feasible and safe. Larger randomized comparative trials are needed to assess the benefits and cost saving of this approach.     

Stent implantation through a self-expanding stent

Jailing of a side-branch is a known complication of stent implantation, and makes access to the side-branch difficult, especially if the stent is of the self-expanding type. Although plain balloon angioplasty is feasible for the jailed side-branches, the use of newer devices (a stent, Rotablation or atherectomy) has not been described. We describe a novel way of treating a side-branch jailed by a self-expanding stent by using stent implantation through the strut of a self-expanding stent.     

Oxidative stress in myocardial ischaemia reperfusion injury: a renewed focus on a long-standing area of heart research

Advances in the treatment of coronary artery disease have seen a significant drop in mortality and morbidity particularly amongst patients with acute myocardial infarction (MI). In particular, percutaneous trans-luminal balloon angioplasty (PTCA) with stenting to re-open atherosclerotic coronary arteries has yielded marked improvement in clinical outcome for patients with acute MI. Furthermore, with the advent of drug-eluting stents occurrence rates for coronary artery restenosis, one common clinical problem associated with angioplasty and stent deployment, have declined markedly. However, coronary restenosis in diabetic patients remains an on-going problem. The success of drug-eluting stents has seen a renewed focus on myocardial ischaemia reperfusion (IR) injury as this represents one area of research where many questions remain unanswered. In particular, the relationship between myocardial IR injury and decreased myocardial micro-vasculature re-flow post PTCA (that ultimately leads to poor clinical outcome and myocardial damage/dysfunction) is one area of research with the potential to decrease current complication rates further in patients suffering myocardial IR injury sustained during MI. This review discusses the role for oxidative stress, oxidant source(s) and both gene regulation and stem-cell therapy as potential strategic targets in the ischaemic myocardium, with the ultimate aim of providing significant cardioprotection in the setting of acute MI.     

The effects of stenting on coronary endothelium from a molecular biological view: Time for improvement?

Coronary artery stenting following balloon angioplasty represents the gold standard in revascularization of coronary artery stenoses. However, stent deployment as well as percutaneous transluminal coronary angioplasty (PTCA) alone causes severe injury of vascular endothelium. The damaged endothelium is intrinsically repaired by locally derived endothelial cells and by circulating endothelial progenitor cells from the blood, leading to re‐population of the denuded regions within several weeks to months. However, the process of re‐endothelialization is often incomplete or dysfunctional, promoting in‐stent thrombosis and restenosis. The molecular and biomechanical mechanisms that influence the process of re‐endothelialization in stented segments are incompletely understood. Once the endothelium is restored, endothelial function might still be impaired. Several strategies have been followed to improve endothelial function after coronary stenting. In this review, the effects of stenting on coronary endothelium are outlined and current and future strategies to improve endothelial function after stent deployment are discussed.     

The role of acute wall recoil and late restenosis: results of the OCBAS trial (Optimal Coronary Balloon Angioplasty with Provisional Stenting versus Primary Stent)

Early deterioration of minimal luminal diameter immediately after PTCA, has been associated with an increase of late restenosis. Lesions with no early loss after PTCA have a low restenosis rate. Coronary stents reduce restenosis in lesions exhibiting early wall recoil. The purpose of the OCBAS study was to compare two strategies during coronary interventions; provision vs. elective stenting. 116 patients with good PTCA results were randomized to stent (n = 57) or to optimal PTCA (n = 59). After randomization in PTCA group, 13.5% of the patients crossed over to stent due to early loss (provisional stenting). Baseline demographic and angiographic characteristics were similar in both groups of patients. At 7.6 months, 96.6% of the entire population had a follow-up angiographic study; 98.2% in the stent and 94.9% in the PTCA group. Immediate and follow-up angiographic data showed that acute gain was significantly higher in the stent than in the PTCA group (1.95 vs. 1.5 mm; P < 0.03). However, late loss was significantly higher in the stent than the PTCA groups (0.63 +/- 0.59 vs. 0.26 +/- 0.44, respectively; P = 0.01). Hence, net gain with both techniques was similar (1.32 +/- 0.3 vs. 1.24 +/- 0.29 mm for the stent and PTCA groups respectively; P = NS). Angiographic restenosis rate at follow-up (19.2% in stent vs. 16.4% in PTCA; P = NS) and TVR (17.5 in stent vs. 13.5% in PTCA; P = NS) were also similar. Furthermore, event-free survival was 80.8% in the stent versus 83.1% in the PTCA group (P = NS). Overall costs (hospital and follow-up) were US$591,740 in the stent versus US$398,480 in the PTCA group (P < 0.02). The strategy of the PTCA with delay angiogram and provisional stent if early loss occurs, had similar restenosis rate and TVR than universal use of bare stents.     

Rat carotid artery dilation by PTCA balloon catheter induces neointima formation in presence of IEL rupture

The best animal angioplasty model is the porcine model, which is expensive and not available in all laboratories. The aim of this study was to describe a new rat model of angioplasty. An injury was induced with the use of a standard percutaneous transluminal coronary angioplasty (PTCA) 1.5-mm balloon catheter. The neointimal tissue, arterial dimensions, and the injury index were assessed following angioplasty. Ki-67 expression was detected to evaluate cell turnover after balloon angioplasty. In contrast with the standard Clowes model, a significant neointimal formation was detected only in the presence of ruptured internal elastic lamina (IEL). A positive correlation between the percentage of ruptured IEL and the amount of neointimal tissue was also demonstrated. The percentage of IEL fracture correlates with the proliferation index by anti-Ki-67 immunolabeling 7 and 14 days after the angioplasty. Significant arterial negative remodeling was observed following PTCA balloon dilation. In conclusion, our inexpensive animal model of restenosis after angioplasty may have great relevance toward a better understanding of the mechanisms and toward assessment of new therapeutical strategies for this phenomenon.     

Clinical trends in stent treatment of simple and complex coronary disease

This is a retrospective analysis of a consecutive group of patients from a single medical center who underwent stent implantation. It describes 316 patients who constituted 53% of the angioplasty procedures carried out in a single year. The authors describe the complications and their 1-year follow-up. We aimed to study the short and long-term results of stenting in our centre in relation to multiple clinical and angiographic variables. During 1996, 316 consecutive patients were treated with stent implantation for a total of 381 coronary lesions. The pharmacological protocol methods of stent implantation and patient characteristics were used. Clinical variables were: age 59.1 3 10.7 years, diabetes mellitus 25.3%, hypertension 33.0% and angina pectoris 88.7% (unstable in 44.1%). Previous coronary surgery had been undergone by 9.2%. Multivessel disease was present in 56% of the patients. The indications for stenting were: primary 58.5%, suboptimal results 33.0% and threatened or acute occlusion 8.5%. Angiographic success was 98.9% and clinical success 96.8%. The major in-hospital complications were acute myocardial infarction (2.2%), acute revascularization (0.3%) and major bleeding (0.6%). All occurred within 24 h of revascularization. Repeated angiography was performed in 115 cases (30.2%) at 160.3 3 109.4 days after stent procedure for unstable angina (38.7%), stable angina (26.1%) and other causes (35.2%). The restenosis rate in those catheterized was 38.1%, with an overall clinical restenosis rate of 11.3% during the follow-up period. Restenosis was more prevalent among diabetic patients (17.9 vs 9.15%, P 3 0.02) and patients with prior balloon angioplasty (18.6 vs 9.75%, P 3 0.046). Clinical follow-up was available in 90.8% of the patients for 291 3 112 days. The actuarial survival at the end of the follow-up period was 93.8%. Death/myocardial infarction was associated with unstable angina pectoris (P 3 0.006), hypertension (P 3 0.001), smoking (P 3 0.046) and threatened or acute occlusion (P < 0.001). In the first year of extensive stent use, stenting is associated with high technical and clinical success rates. Long-term results after stent implantation are associated with the occurrence of acute or threatened occlusion, and the in-hospital complications diabetes mellitus and hypertension.     

可降解冠状动脉支架的研究进展

冠脉内支架植入是临床上预防PTCA术后再狭窄并发症的有效措施,但金属支架仅在植入早期发生作用,在冠脉内壁修复完成后则成为多余的负担,可能激活血小板及多种凝血因子聚集导致血栓形成及刺激血管壁造成心脏事件及再狭窄的发生。针对上述问题,生物可降解冠状动脉支架的研究得到了相当的发展。本文就可降解支架的发展及现状作一简要综述。